Elevator systems are built into buildings. They comprise an elevator car which, via suspension means such as suspension ropes or suspension belts, is connected to a counterweight or to a second elevator car. By means of a drive, which can be chosen to act on the suspension means, or directly on the car or counterweight, the car is moved along essentially vertical guiderails. The elevator system is used to transport persons and goods between one or more stories in the building.
The elevator system contains apparatus to secure the elevator car in case of failure of the drive or of the suspension means, or to prevent undesired drifting away or falling when stopping at a floor. For this purpose, safety gears are generally used which, in case of need, can brake the elevator car on the guiderails.
Historically, such safety gears were actuated by mechanical speed governors. Today, however, electronic monitoring devices are also used, which, in case of need, can activate braking apparatus or safety gears.
So as to be able nonetheless to rely on known safety gears, electromechanical actuating units are often required which, when correspondingly triggered, can actuate safety gears.
From EP0543154 such a device is known. By its means, in case of need, an auxiliary caliper brake is brought into engagement with a guiderail, and this auxiliary caliper brake actuates an existing lever system, by means of which safety gears are actuated. This auxiliary caliper brake is designed to be able to move the lever system and mass components of the safety gear, or to actuate the safety gear. The electromagnetic units are dimensioned correspondingly large.
From WO 2008/057116 a similar device is known. By this means, in case of need, a coupler body that is arranged in a safety gear is pressed against a guiderail, whereby the safety gear is actuated.
From U.S. Pat. No. 7,575,099 a further such device is known. In this solution, in case of need, engagement wedges of a safety gear are actuated directly by springs. The springs are pretensioned by an electromagnet and, in case of need, the pretensioned springs are released. The springs can be reset or retensioned again by means of a spindle drive. This electromagnet is dimensioned correspondingly large, since the entire pretension force of a plurality of springs should be absorbed directly and held.